Study On Corrosion Behavior Of Steel In Simulated Polluted Atmospheric Environment

The study on corrosion behavior of steel develops speedly in atmospheric enviro-nment recently. The corrosion of Q235steel and weathering steel is investigated on theShenyang industrial atmospheric exposure test and the indoor accelerated corrosion test.The corrosion resistance of Q235steel is compared with weathering steel in differentatmospheric environment.Simulated marine atmospheric accelerated corrosion test is done with3.5%NaCl asthe corrosive medium. Simulated industrial atmospheric accelerated corrosion test isdone with0.01mol/L NaHSO3as the corrosive medium. Simulated marine and indust-rial atmospheric accelerated corrosion test is done with3.5%NaCl,0.01mol/L NaHSO3,0.01mol/L NaHCO3and0.01mol/L NaNO3as the corrosive medium.By comparing the corrosion behavior of Q235steel in Shenyang industrial atmosp-heric environment with indoor simulated industrial atmospheric accelerated corrosiontest, Q235steel corrosion weight loss curve trend is similar in both tests. The main com-ponents of the rust layer are Fe2O3、α-FeOOH and γ-FeOOH. The rust layer has no pro-tection. It is illustrated that acceleration and correlation exist between indoor acceleratedtest and atmospheric corrosion. So the corrosion behavior of steel in atmosphere enviro-nment can be simulated by indoor accelerated corrosion test.Contrasted the corrosion condition of Q235steel and weathering steel in indoorsimulated marine, industrial and marine industrial accelerated corrosion test. The massloss analysis indicates that, weight loss of the both steels is similar and weathering steelhas no advantage in simulated marine atmospheric accelerated corrosion test. The massloss of the weathering steel is shorter than Q235steel in simulated industrial and marine.The corrosion resistant of the weathering steel is better than Q235steel in industrial andmarine industrial atmospheric accelerated corrosion tests. In this three kinds of accelera-ted corrosion tests, it can be got from XRD that the main corrosion products of the bothsteels are α-FeOOH and γ-FeOOH. In simulated marine atmosphere accelerated test, therust layer of steel contains β-FeOOH. In simulated industrial atmosphere acceleratedtest, the rust layer of steel contains FeSO4.From SEM we can get that the rust layer is thin and loose in former. The rust layer is thick in later. The rust layer of weatheringsteel is a dense. EDS indicated that the alloy elements in weathering steels graduallyshifted to the inner rust layer to protect the steel. So weathering steel has bettercorrosion resistance. The electrochemical analysis shows that the rust layer can inhibitthe anodic metal dissolution. The protective effect of rust layer of steel is enhanced. Sothe corrosion resistant of the weathering steel is not obvious in marine atmosphericenvironment. The weathering steel is not suitable in marine atmospheric environment,but it is suitable in industrial and marine industrial atmospheric environment.